Justification of sensitivity of the immunochromatographic analysis depending on localization of the detected antigen

The aim of the work was to determine the effect of localization of the detected antigen on the sensitivity of the immunochromatographic method. The sensitivity of the immunochromatographic test system "RED Helicobacter pylori" intended for the detection of the ferment of H. pylori-urease was evaluated. As the test material used a pure culture of H. pylori, as well as the commercial antigen AGHPY-0100 ("Arista Biologicals", USA), composed of intracellular H. pylori proteins associated with cagA genes (120 kd) and vacA (87 kDa) and urease. According to the results of testing with commercial antigen AGHPY-0100, the sensitivity threshold of the test system "RED Helicobacter pylori" was not less than 20 ng/ml, which indicates a high sensitivity of the test system. When tested with whole corpuscular culture of H. pylori, the sensitivity was significantly lower and amounted to 1.1×1010 cm-3. Experimental data confirm the hypothesis that if the immunochromatographic test system is aimed at the detection of intracellular antigen, then high sensitivity can be achieved only by testing the pre-isolated and purified antigen of the microorganism. When developing such test systems, it can be expected that they will be mostly qualitative, not quantitative.